The field of the disclosure relates generally to fiber optic equipment and more particularly to methods and assemblies for securing an optical fiber to a ferrule, which may be used within fiber optic connectors.
Benefits of optical fibers include extremely wide bandwidth and low noise operation. In cases where high bandwidth is required between two interconnection locations, fiber optic cables having fiber optic connectors may be used to communicate information between these locations. The fiber optic connectors may also be used to conveniently connect and disconnect the fiber optic cables from the interconnection locations when maintenance and upgrades occur.
Each of the fiber optic connectors may include a ferrule assembly having a ferrule and an optical fiber. The ferrule has several purposes. The ferrule includes an internal pathway, called a ferrule bore, through which the optical fiber is supported and protected. The ferrule bore also includes an opening at an end face of the ferrule. The opening is where an optical surface of an end portion of the optical fiber may be precisely located to be proximate to an optical surface of an end portion of another optical fiber of a complementary connector. The end portion of the optical fiber needs to be precisely secured to the ferrule or the optical fiber may move within the ferrule bore, resulting in an uncertain position between the optical surface of the optical fiber and the optical fiber of the complementary connector. In this regard, an unwanted gap may develop between the proximate optical fibers and signal loss, otherwise known as attenuation, may occur.
A bonding agent, for example an epoxy resin, is one approach to secure the optical fiber to the ferrule, but there are manufacturing issues with this approach. Specifically, the ferrule is first assembled to a fiber optic connector housing to minimize mechanical assembly from occurring when the optical fiber is disposed within the ferrule bore and to facilitate the assembly process. The optical fiber and an uncured bonding agent are later inserted within the ferrule bore. The optical fiber may then be secured to the ferrule by a process called “curing” of the bonding agent. Curing is a chemical process specific for different types of bonding agents wherein the bonding agent forms cross-linked thermoset structures, thus enabling secure bonds to be created between proximate objects. For many bonding agents compatible to secure the optical fiber to the ferrule, heat is required to bring the temperature of the bonding agent to a securing temperature, which may be from approximately eighty-five (85) to two-hundred (200) degrees Celsius, to facilitate the bonding required of the bonding agent during curing to secure the optical fiber to the ferrule. If the temperature does not reach this value, then a reduced percentage of bonding may occur, and the optical fiber may be inadequately secured to the ferrule. To provide the heat to elevate the temperature, the optical fiber and ferrule are typically heated in an oven relatively slowly, for example approximately twenty (20) minutes, to elevate the temperature of the bonding agent without damaging the fiber optic housing, which may be damaged by applying more intense heat to speed curing. The relatively slow heating process to protect the housing imposes a significant restriction on manufacturing efficiency.
Other heating devices, such as lasers, have been used to heat ferrules, and thereby cure the bonding agent disposed therein, so that faster curing can occur. However, for ferrules mostly enclosed within fiber optic connector housings, lasers are used only to directly heat merely a tip of the ferrule to avoid damaging the fiber optic connector housing. Laser heating only the tip may result in poor adhesion between the optical fiber and the ferrule, because the amount of bonding agent that is cured is insufficient to provide the strength needed for many fiber optic connector applications. Further, the bonding agent located at the tip of the ferrule may be damaged from intense local heating from the laser.
It is noted that other examples of the bonding agents, for example, adhesives and/or cohesives, may be used without the curing involving cross-linked thermoset materials, but may be thermally activated by heating to a securing temperature so that the optical fiber may be secured to the ferrule. For these other bonding agents, the technical challenge remains the same, wherein heat needs to be delivered to the bonding agent without damaging the fiber optic connector housing.
What is desired is a more cost-effective and efficient method to secure the optical fiber to the ferrule, to minimize attenuation without damaging the fiber optic connector housing.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.